To prevent leakage of body exudates from absorbent articles such as feminine care pads or napkins and disposable diapers, it is desirable that the exudates not reach the edges of the absorbent material in the article. A “center fill” strategy is desirable for leakage control, wherein fluids are preferentially held in a central region of the article. Further, absorbent articles with center fill strategies are desirable for the clean appearance they offer and the reduced wetted area in contact with skin. Unfortunately, in traditional absorbent articles, there is generally no barrier to bulk flow or capillary wicking from the target region to the edges of the article.
Efforts to prevent leakage from the sides of absorbent articles include using fluid impervious cuffs and flaps. These added barriers are costly and do not prevent fluid from reaching the edge of the absorbent article, though they can be effective in reducing leakage in some absorbent articles.
Central meltblown strips and other narrow strips of absorbent material have been added to the body side of absorbent articles to promote center filling of the articles. However, meltblown strips interfere with absorption of fluid into the absorbent cellulosic portions of the article and can hold wet fluid near the skin. Other efforts at controlling fluid intake to promote central filling have used narrow strips of cellulosic or other absorbent material with a horizontal barrier between the strip and the underlying absorbent core. The horizontal barrier material for delaying wicking provides vertical isolation of the central strip from the absorbent core, but does not prevent flow out of the sides of the wetted strip or toward the sides of the article. Further, the horizontal fluid barrier often occupies a significant portion of the article's surface area and can result in ineffective use of the underlying absorb nt core.
Embossing has also been used to promote longitudinal fluid flow, but embossments generally are not successful in preventing lateral wicking and in promoting true center fill. Furthermore, heavy embossing can be an ineffective use of absorbent material since the embossed regions are typically highly densified, generally having little pore volume for absorption of fluid.
Longitudinal chambers have also been used wherein each channel or chamber of absorbent material is completely isolated from the next by means of impervious or flow restricting walls. In some cases, however, isolated chambers represent a poor use of absorbent material as one chamber may become overloaded and overflow onto the cover, resulting in smearing and inefficient use of the absorbent material in other chambers. Successful use of isolated chambers requires improvements for prevention of chamber overflow, prevention of undesirable surface transport and smearing, and improved use of the absorbent material in the absorbent article. Further, prior attempts at isolated flow chambers are generally complex in execution, costly, and may suffer from poor product integrity. Improved approaches are needed that can be mass produced for low cost while achieving high levels of performance.
In general, what is needed is an improved means for promoting center fill and reducing flow toward the edges of the absorbent article for leakage reduction that offers improved feel and appearance of the article while also reducing smearing or other forms of failure.